The present invention relates to improvements in electrode plates for battery and a battery using the improved electrode plates for battery.
In order to prevent falling of an active material off a current collector of a battery due to usage of repeated charge/discharge operations or during the assembly work of batteries, an application of a chromate treatment or a corona discharge treatment to the surface of the current collector has so far been proposed. (The Japanese Patent Unexamined Publication Nos. S56-57261 and H7-135023) Also, relative to the manufacturing of electrode plates for a lithium-ion secondary battery, a method of performing dispersion by kneading under the presence of a surface-active agent is disclosed as the method for improving the wettability of an active material against a bonding agent and a viscosity improver. (The Japanese Patent Unexamined Publication No. H8-190912)
However, it is found difficult for the foregoing electrode plates for battery to achieve an improvement in wettability of an active material against a bonding agent and a viscosity improver and also to satisfy the required adhesiveness between a current collector and an active material after the active material has been applied to the current collector. As a result, after a storage under high temperatures or during repeated charge/discharge operations, the active material peels and falls off the current collector, thereby causing the problem of a reduction in charge/discharge capacity.
The present invention deals with the foregoing unsettled problem to realize a lithium-ion secondary battery which shows minimal corrosion of a current collector due to an active material, minimal peeling and falling of the active material off the current collector, thereby demonstrating large discharge capacity.
The present invention deals with the afore-mentioned problem to provide an electrode plate for battery and a battery using it, the electrode plate for battery being characterized by applying a boehmite treatment to the surface of a current collector prior to an application of a paste, which is formed of a composition with an active material acting as the principal ingredient, to the current collector.
With a method for producing electrode plates for lithium secondary battery characterized by applying a paste containing a positive electrode active material to a current collector formed of a metallic foil and then drying the paste, the current collector is applied with a chromate treatment on the surface thereof to form a chrome oxide layer prior to the foregoing application of the paste.
The present invention discloses a method for producing electrode plates, the method comprising the steps of:
applying a boehmite treatment to the surface of current collector of one electrode plate selected from a positive electrode plate and a negative electrode plate or applying a chromate treatment to the surface of a positive electrode current collector;
applying a paste formed of a composition containing an electrode active material on the current collector; and
drying the paste.
Even when a battery employing the electrodes as described in the above is in usage with repeated charge/discharge operations, a reduction in the charge/discharge capacity and degradation in the load characteristics can be suppressed to a minimum.